All you need to do is add the words that Our Lord said to put on this picture, "Jesus, I trust in You!" He told St. Faustina to have this vision painted with those words on it since He is coming back soon and wants us to start adoring Him and using this picture when we ask for His Mercy. He established the Divine Mercy Sunday on the First Sunday after Easter and told us to say the Chaplet of Divine Mercy every day at 3PM. God bless you all!